Usage:
The timing procedure shown in this instruction is for tandem D398-G398 Engines and tandem D399-G399 Engines. Get the timing procedure on other model combinations from Caterpillar Industrial Division Engineering. For information on the original installation and alignment of tandem engines, see the engineering drawings given with the specific engine and coupling group and Form No. LEHM1469, "CATERPILLAR MARINE ENGINE APPLICATION AND INSTALLATION GUIDE".
(1) Remove cover (1) from the flywheel housing on both engines. Remove the valve cover from the No. 1 cylinder on both engines. Turn the crankshaft of the No. 2 engine (the engine nearest the driven load) in the normal direction of rotation until timing pointer (2) is in alignment with the "TC 1-11" mark on the flywheel of D398-G398 engines or the "1-15" mark on the flywheel of D399-G399 engines as shown. There must be no movement of intake valve (3) or exhaust valve (4) when the flywheel is moved 2" (50) before or after this timing mark. If there is movement of either valve, turn the crankshaft 360° in the normal direction of rotation until the timing pointer is again in alignment with the "TC 1-11" or "1-15" mark on the flywheel. The No. 1 piston is now at top center compression stroke and must not be moved until both engines are connected together.
(2) Install coupling shaft (5) on the front of the No. 2 engine with the mark "TOP" on the shaft up when the No. 1 piston is at the top center position. Shaft runout must not be more than .010" (0.25) around location (A) with the indicator base fastened to the front accessory drive housing.
(3) On D398-G398 Engines only, turn the crankshaft of the No. 1 engine (the engine farthest from the driven load) in the normal direction of rotation until timing pointer (2) is in alignment with the "TC 1-11" mark on the flywheel as shown. Exhaust valve (4) has just closed and intake valve (3) is just starting to open. If there is no movement of either valve when the flywheel is moved 2" (50) before or after the "TC 1-11" mark, turn the crankshaft 360° in the normal direction of rotation until the timing pointer is again in alignment with the "TC 1-11" mark. The No. 1 piston is now at top center exhaust stroke and must not be moved until both engines are fastened together. The engines are now correctly timed and ready to be connected together with the No. 1 cylinder of each engine firing 360° apart.
(4) On D399-G399 Engines only, turn the crankshaft of the No. 1 engine (the engine farthest from the driven load) in the normal direction of rotation until timing pointer (2) is in alignment with the "1-15" mark on the flywheel as shown. Exhaust valve (4) has just closed and intake valve (3) is just starting to open. If there is no movement of either valve when the flywheel is moved 2" (50) before or after "1-15" mark, turn the crankshaft 360° in the normal direction of rotation until the timing pointer is again in alignment with the "1-15" mark. Now turn the crankshaft an additional 45° past the "1-15" mark in the normal direction of rotation. The timing pointer must be on the mark halfway between 10° and 20° before top center of "2-16". Both engines are now correctly timed and ready to be connected together with the No. 1 cylinder of engine No. 2 firing 405° after the No. 1 cylinder of engine No. 1.
(5) Install the coupling on the flywheel of the No. 1 engine. Inner coupling (6) must be installed with a tooth (B), that is not in alignment with a hole (C), in the position shown when the timing pointer of the No. 1 engine is on the correct mark on the flywheel.
(6) After the engines are connected, the end clearance of the coupling must be .34" ± .03" (8.6 ± 0.8) as shown by dimension (X). Face runout as shown by indicator (7) must not be more than .008" (0.20). Bore runout as shown by indicator (8) must not be more than .008" (0.20). Install the valve cover and the cover on the flywheel.